Broken ankles. Twisted knee. Real calls to EMS by area trampoline parks. Critics and park owners want people to know the risks are real.

GREENSBORO, NC -- Trampoline parks are springing up in record numbers. Adults and kids alike seem to enjoy them....and get hurt there. That's what Two Wants to Know team found when they looked through 911 medical call records to those parks. As Lechelle Yates discovered both critics and park owners want people to know the dangers of jumping for fun.

Ceresa Cecil brought her godson Ethan to Airbound Trampoline Park in Greensboro for a little birthday fun. "It's a great way to stay active."

She signed a waiver. And she saw the warning signs. Neither really made her think about possible dangers. I know when I got here I was like, 'Oh I have to sign the waiver,' but you think about it, lots of places you go, you've got to sign a waiver."

You might need to sign a waiver because people are getting hurt at trampoline parks. Airbound Trampoline Park opened in Winston-Salem in March 2012 and in Greensboro August 2013. 9-1-1 records show EMS made 11 trampoline -related visits to the parks since then. We counted calls for an injury with bleeding, a twisted knee and broken ankles.

The Child Injury Prevention Alliance says its organization is seeing unnecessary injuries in trampoline parks. Dr. Gary Smith says, "There is not enough supervision and they're not being used appropriately."

No government guidelines control jump parks yet, but Airbound follows a voluntary standard of one monitor for every 32 jumpers. The monitors explain and enforce the rules and the rules are written everywhere. Still not everyone listens. ATP co-owner Andy Baer steps in on a court to talk to a jumper. "You're not jumping for five minutes. I just told you not to and you went and did it. You have to sit down."

Andy says, "The kids think that they are better than the rules or think, 'I don't have to follow them,' they're the ones that get hurt because they're doing the things they shouldn't be doing."

Baer says his stats show kids are more likely to get injured in organized sports. But he says a sprained ankle can happen. It is an extreme sport after all. "Obviously we're striving to make that number zero. I don't like seeing people get hurt but obviously sometimes there are risks to having fun. We try to minimize risk as much as possible."

Ceresa says all the supervision made her feel safe, but she felt some responsibility as well. "It definitely can be dangerous if you're not paying attention."

Other safety features at the park: - every trampoline has another one underneath it in case the top one rips you won't fall to the floor - the springs are covered with heavy pads - netting keeps jumpers inside the court

Backyard trampolines actually account for the majority of the injury statistics you see. Typically because they have the least supervision.

Broken ankles. Twisted knee. Real calls to EMS by area trampoline parks. Critics and park owners want people to know the risks are real.